The invention discloses a device for sealing an inlet pipe of an overflow ball mill, which comprises a connecting flange, a horn-shaped sealing gasket, a stressed pad and fixing flanges. The connecting flange is fixedly connected with a flange for the inlet of the ball mill; the inlet pipe is provided with the horn-shaped sealing gasket, the stressed pad and the fixing flanges in sequence; the horn-shaped opening of the horn-shaped sealing gasket faces to the connecting flange; the horn-shaped sealing gasket is made of rubber; the external diameter of the horn-shaped sealing gasket is less than the aperture of a connecting flange and ball mill cross section connection bolt, and the internal diameter matches with the external diameter of the inlet pipe; the fixing flanges are two semicircular connecting components; and at least six stressing and compressing parts are uniformly arranged the circular surfaces of the fixing flanges. The device disclosed by the invention has the advantages of low investment, simple configuration, convenience of installation and obvious effect. Due to the adoption of the device, the site can be kept neat and clean, the labor intensity of the operators on the site and the equipment maintenance time and frequency can be reduced greatly, and the equipment can work stably for a long period and is more convenient to change.